The Impact of miR-155-5p on Myotube Differentiation: Elucidating Molecular Targets in Skeletal Muscle Disorders

MicroRNAs are small regulatory molecules that control gene expression. An emerging property of muscle miRNAs is the cooperative regulation of transcriptional and epitranscriptional events controlling muscle phenotype. miR-155 has been related to muscular dystrophy and muscle cell atrophy. However, the function of miR-155 and its molecular targets in muscular dystrophies remain poorly understood. Through in silico and in vitro approaches, we identify distinct transcriptional profiles induced by miR-155-5p in muscle cells. The treated myotubes changed the expression of 359 genes (166 upregulated and 193 downregulated). We reanalyzed muscle transcriptomic data from dystrophin-deficient patients and detected overlap with gene expression patterns in miR-155-treated myotubes. Our analysis indicated that miR-155 regulates a set of transcripts, including Aldh1l, Nek2, Bub1b, Ramp3, Slc16a4, Plce1, Dync1i1, and Nr1h3. Enrichment analysis demonstrates 20 targets involved in metabolism, cell cycle regulation, muscle cell maintenance, and the immune system. Moreover, digital cytometry confirmed a significant increase in M2 macrophages, indicating miR-155's effects on immune response in dystrophic muscles. We highlight a critical miR-155 associated with disease-related pathways in skeletal muscle disorders.

Biological effects of the antihypertensive losartan under different ocean acidification scenarios

Since the last decade, several studies have reported the presence and effects of pharmaceutical residues in the marine environment, especially those of the antihypertensive class, such as losartan. However, there is little knowledge about the physiological effects of losartan in marine invertebrates regarding its behavior under possible coastal ocean acidification scenarios. The objective of this study was to evaluate biological effects on marine organisms at different levels of the biological organization caused by the compound losartan in water and sediment under coastal ocean acidification scenarios. Water and sediment samples were collected at five sites around the Santos Submarine Sewage outfall (SSO) and two sites around the Guarujá Submarine Sewage Outfall (GSO). Losartan was found in concentrations ranging from <LOD to 7.63 ng/L in water and from <LOQ to 3.10 ng/g in sediments. Statistical analysis showed interactive effects pH and losartan on the toxicity results. The water toxicity test with Echinometra lucunter embryos/larvae showed LOECs 50-100 mg/L, with values decreasing as the pH decreased. In the sediment assays, LOEC value for sea urchin embryo-larval development was 1.0 μg/g for all tested pHs. Regarding the lysosomal membrane stability assays with adult bivalves, a LOEC of 3000 ng/L was found for Perna perna in water exposure (both at pH 8.0 and 7.6). Effects for Mytella guyanensis were observed at environmentally relevant concentrations in sediment (LOEC = 3 ng/g at pH 8.0 and 7.6). This study demonstrated that coastal ocean acidification by itself causes effects on marine invertebrates, but can also increase the negative effects of losartan in waterborne exposure. There is a need to deepen the studies on the ecotoxicity of pharmaceutical residues and acidification of the marine environment.

Multiple endocrine neoplasia type 2A. Study of a family

INTRODUCTION

Pheochromocytomas (Pheo) can occur sporadically, isolated or in association with other neuroendocrine lesions. In multiple endocrine neoplasia type 2A (MEN-2A), Pheo is associated to medullary thyroid carcinoma (MTC) or its precursor, C-cell hyperplasia (CCH) and parathyroid hyperplasia. Genetic screening provides early diagnosis and preventive treatment. In order to validate DNA analysis as a reliable method of early identification of gene carriers, we compared the results of genetic screening with clinical, biochemical, imaging and pathological findings in the members of an affected family.

POPULATION AND METHODS

The diagnosis of a bilateral necrotic Pheo in a female patient led to the study of a family with four generations, aged 3 to 78 years (mean = 30.3 yrs). The study included a clinical examination; basal and pentagastrin stimulated calcitonin values; urinary catecholamines and their metabolites; serum calcium and a genetic study (direct sequence of PCR products from genomic DNA isolated from leucocytes using specific primers in exon 11 of the RET protooncogene of chromosome 10). The radiologic study, gammagraphic study (131I-MIBG) and magnetic resonance study were performed in members with clinical suspicion of Pheo.

RESULTS

Seven out of nine patients had a mutation on codon 634 of exon 11 of RET (TGC-CGC), leading to cysteine arginine substitution in the codified protein; all gene carriers had biochemical markers of MTC/CCH and four of Pheo. The Pheo patients underwent adrenalectomy (bilateral in three) and all the gene carriers underwent prophylactic thyroidectomy. The pathologic findings were: MTC in four (metastasized in one); CCH in three and parathyroid hyperplasia in one.

CONCLUSIONS

Phenotypic penetration of RET mutation was 100% for MTC/CCH, but only 57% of the gene carriers had Pheo. Genetic screening allowed early prophylactic treatment in four out of seven patients; pathologic findings revealed several evolutionary stages of the disease. Patients not yet showing Pheo are under close clinical and laboratory surveillance.